There is known a sound correction system in which frequency characteristics of spatial sound fields of an audio device are corrected to be adequate for a listener position. In the sound correction system, for example, given test sound (white noise, etc.) is output from a speaker of an audio device, and the sound is collected with a microphone arranged at a listener's position. Then, the frequency characteristics of the sound are analyzed to calculate a correction value for obtaining a target frequency characteristic. The sound correction system adjusts an equalizer of the audio device based on the calculated correction value. Thus, the listener can listen to sound having the target frequency characteristics obtained through correction that is output from the audio device.
There is also known a sound correction system in which test sound is collected using a mobile terminal with a microphone embedded, such as a smartphone (multifunctional mobile phone, personal handyphone system (PHS)). In this case, the mobile phone collects test sound output from a speaker of an audio device using an embedded microphone, and transmits measured data or analysis results of the measured data to the audio device. The use of such a mobile terminal can reduce costs of the sound correction system.
In the conventional sound correction system, a correction value calculated based on analysis results of collected sound depends on the quality of a microphone (quality of measuring system) used for collecting sound. For example, the microphones of mobile terminals have different specifications depending on manufacturers, models, etc. In a mobile terminal, an inexpensive microphone may be used to reduce costs. Such inexpensive microphones cause process variations. Thus, the reliability of frequency characteristic measurement results is deteriorated.